I'm sure they used to be far more expensive than they are now, but they're easier to make these days and, more importantly, a necessary tool to do business. [ For anybody in the medical field, anyway.

Still, he seems more interested in the stethoscope. They must not have these where he's from. It's hard for Maomao to imagine a world without them (ironically.) ]

If you'd like, you can try it out. [ She offers him the other end of the stethoscope as well. ] Just put the two ends into your ears, then place the flat part against your chest - under your shirt. You can hear your own heartbeat of the sound of your breathing quite well.